The present invention relates to a pharmaceutical composition comprising fixed dose combination of metformin and vildagliptin or pharmaceutically acceptable salt thereof. The composition comprises a core and layers coated on the core, wherein the core comprises first active and coat or layer on the core comprises second active. Such compositions exhibits relatively improved storage stability and particularly, levels of degradants in the formulation during storage can be effectively controlled and have desired release profile. The invention also includes a process of preparing such compositions and method of treating type-2 diabetes mellitus by administering the composition to a patient in need thereof.
